Agricultural harvester/threshers or "combines" are typically equipped with harvesting "headers" which include a cutter mechanism for cutting the crop and a feeder mechanism which feeds the cut crop into the combine feeder housing mounted on the front of the combine. The cut crop material is conveyed into the combine via a feeder housing which includes a chain driven crop feeder conveyor. These crop feeder conveyors typically take the form of "chains and slats" in which multiple, parallel chains, e.g. two, three or more, are each entrained around respective coaxial rear drive sprockets and a forward feed drum. The chains are linked together by transverse slats which are operative to move the crop from an inlet of the feeder housing upward along the floor thereof and into the threshing chambers of the combine. Typically, a welded cylindrical guide ring, which resembles a simple rectangular tooth in cross section, is placed around the periphery of the feed drum just outboard (or inboard) of each chain location to help hold the respective chain in position about the feed drum.
A number of problems occur in these prior art chain and slat crop conveyors. For example, it is difficult to keep the chains running straight, i.e. the chains tended to wander from side to side and often rode up and over the welded guide rings "teeth". This chain wandering often causes the chain to jump a tooth on the drive sprocket, which stretches it and drastically reduces chain life. In these prior art systems, the side bars of each chain run directly on the surface of the feed drum. The metal to metal contact between the chain side bars and the feed drum surface which occurs due to the relative motion between the chain side bars and the feed drum causes the feed drums to wear rapidly. Repair or replacement of chains and/or drum is an expensive exercise which necessitates dismantling of the feeder housing and consequent machine down time.
At least one attempt has been made to address this problem, as reflected in U.S. Pat. No. 5,346,429 to Herb Farley, and entitled FEEDER ASSEMBLY FOR A COMBINE. In the Farley patent, a series of elastomeric chain supports are positioned around the feed drum. Each of the chain supports is cylindrical in shape and includes a central chain supporting rim positioned between outer, larger circumference annular rims such that a respective track is formed for accommodating each chain. The chain supports in the Farley patent are designed to be noise reducing due to the elastomeric material, however, they have a limited life due to their resilient nature. Accordingly, relatively frequent replacement of the wear rings is required. Furthermore, the annular rims of the chain supports in the Farley patent are perpendicular to the drum surface, and thus do not provide any chain tensioning as the chains start to wander, i.e. the chains can jump over the annular rims just as they do the prior art guide teeth.
It is clear then, that an improved combine crop feeder conveyor is needed. Such a crop feeder conveyor should include chain guide rings about the feed drum which are durable, which prevent the chain side bars from direct metal to metal contact with the drum or guide ring surface and which prevent tend to keep the chains running straight, thus preventing them from jumping a tooth in the respective drive sprocket.